Method of Synthesis of a Compound LiM1-x-y-zNyQzFexPO4 and Use Thereof as Electrode Material for a Lithium Battery

Abstract

The invention relates to a method of manufacture of a compound of formula LiM 1-x-y-z N y Q z Fe x PO 4 , the compound thus obtained, and to a method of manufacture of a composite material comprising LiM 1-x-y-z N y Q z Fe x PO 4 and carbon, the composite material thus obtained, as well as an electrode comprising this composite material, and a lithium battery comprising such an electrode, in which: M is a transition element selected from Co, Ni, Mn and Fe; N is a doping element different from M and Q; Q is a transition element selected from Co, Ni, Mn and Fe but different from M; 0≦x≦1; 0≦y≦0.15; 0≦z≦1; and 0<x+y+z≦1.

1 . A method of manufacturing a compound of the following formula I:
   LiM 1-x-y-z N y Q z Fe x PO 4   formula I
   
       in which:
 M is a transition element selected from the group consisting of Co, Ni, Mn and Fe, 
 N is a doping element different from M and Q, 
 Q is a transition element selected from the group consisting of Co, Ni, Mn and Fe but different from M, 
 0≦x≦1, 
 0≦y≦0.15, 
 0≦z≦1, and 
 0<x+y+z≦1, 
 
       comprising the following steps:
 a) mixing the precursors of Li, M, N, Fe, P and ascorbic acid in an aqueous solvent, 
 b) microwave heating the mixture obtained in step a) at a temperature between 100 and 300° C. and at a pressure between 0.5 and 50 bar for a time between 1 and 60 minutes, and 
 c) washing the product obtained in step b) with ethanol and water. 
 
     
     
         2 . The method according to  claim 1 , wherein in step a), the aqueous solvent comprises a glycol compound and in that the volume ratio of water to glycol compound is between 9 and 1/9. 
     
     
         3 . The method according to  claim 1 , wherein in step a), the amount of ascorbic acid is between 0.01 and 0.5 wt %, relative to the amount of Fe. 
     
     
         4 . The method according to  claim 1 , wherein in step a), the precursor of Li is selected from the group consisting of lithium hydroxide, acetate, nitrate, chloride and hydrogen phosphate. 
     
     
         5 . The method according to  claim 1 , wherein in step a), the precursors of Mn, Fe, Ni and Co are selected from the group consisting of a sulphate, an acetate, an oxalate, a chloride, a hydroxide and a nitrate of respectively Mn, Fe, Ni and Co. 
     
     
         6 . The method according to  claim 1 , wherein in step a), the precursor of phosphorus is selected from the group consisting of phosphoric acid (H 3 PO 4 ), diammonium hydrogen phosphate ((NH 4 ) 2 HPO 4 ) and ammonium dihydrogen phosphate (NH 4 H 2 PO 4 ). 
     
     
         7 . The method according to  claim 1 , wherein in step a), the precursors of M, N, Q, Fe and P are mixed in the desired stoichiometric amounts of M, N, Q, Fe and P in the final compound of formula I and the precursor of Li in an amount of Li greater than the stoichiometric amount in equivalents in moles, than the Li desired in the final compound of formula I. 
     
     
         8 . A method of manufacturing a composite material of the following formula II:
   C—LiM 1-x-y-z N y Q z Fe x PO 4   formula II
   
       in which:
 M is a transition element selected from tl ou consis Co, Ni, Mn and Fe, 
 N is a doping element different from M and Q, 
 Q is a transition element selected from the group consisting of Co, Ni, Mn and Fe but different from M, 
 0≦x≦1, 
 0≦y≦0.15, 
 0≦z≦1, and 
 0<x+y+z≦1, 
 
       comprisescomprising the following steps:
 a) mixing the precursors of Li, M, N, Fe, P and ascorbic acid in an aqueous solvent, 
 b) microwave heating the mixture obtained in step a) at a temperature between 100 and 300° C. and at a pressure between 0.5 and 50 bar for a time between 1 and 60 minutes, 
 c) washing the product obtained in step b) with ethanol and water; and 
 d) mixing the compound thus obtained with carbon powder having a specific surface greater than 700 m 2 /g. 
 
     
     
         9 . An electrode comprising a material of formula I and obtained by the method according to  claim 1 . 
     
     
         10 . A Li-ion battery comprising an electrode according to  claim 9 . 
     
     
         11 . A compound of the following formula I:
   LiM 1-x-y-z N y Q z Fe x PO 4   formula I
   
       in which:
 M is a transition element selected from the ou consist n Co, Ni, Mn and Fe, 
 N is a doping element different from M and Q, 
 Q is a transition element selected from the group consisting of Co, Ni, Mn and Fe but different from M, 
 0≦x≦1, 
 0≦y≦0.15, 
 0≦z≦1, and 
 0<x+y+z≦1, 
 
       obtained by the method according to  claim 1  and having the form of platelets, two dimensions of which are between 20 nm and 500 nm and the thickness of which is between 1 and 100 nm. 
     
     
         12 . A composite material of the following formula II:
   C—LiM 1-x-y-z N y Q z Fe x PO 4   formula II
   
       in which:
 M is a transition element selected from the group consisting of Co, Ni, Mn and Fe, 
 N is a doping element different from M and Q, 
 Q is a transition element selected from the group consisting of Co, Ni, Mn and Fe but different from M, 
 0≦x≦1, 
 0≦y≦0.15, 
 0≦z≦1, and 
 0<x+y+z≦1, 
 
       comprising a compound of formula I according to  claim 11  and carbon and having a specific surface greater than or equal to 80 m 2 /g.